class_docstr: The OCRNet implementation based on PaddlePaddle.
  The differences from OCRNet at OCRNet at paddleseg/models/ocrnet.py are
  
      1. The convolution bias is set to False
  
      2. droput_ rate in SpatialOCRModule is 0.05
  
      3. OCRHead will return `ocr`.
  
      4. Will not Logit_ List size to the original size, when MS_ attention=True
  
  The original article refers to
      Yuan, Yuhui, et al. "Object-Contextual Representations for Semantic Segmentation"
      (https://arxiv.org/pdf/1909.11065.pdf)
  
  Args:
      num_classes (int): The unique number of target classes.
      backbone (Paddle.nn.Layer): Backbone network.
      backbone_indices (tuple): A tuple indicates the indices of output of backbone.
          It can be either one or two values, if two values, the first index will be taken as
          a deep-supervision feature in auxiliary layer; the second one will be taken as
          input of pixel representation. If one value, it is taken by both above.
      ocr_mid_channels (int, optional): The number of middle channels in OCRHead. Default: 512.
      ocr_key_channels (int, optional): The number of key channels in ObjectAttentionBlock. Default: 256.
      align_corners (bool): An argument of F.interpolate. It should be set to False when the output size of feature
          is even, e.g. 1024x512, otherwise it is True, e.g. 769x769.  Default: False.
code: def forward(self, x):
      feats = self.backbone(x)
      feats = [feats[i] for i in self.backbone_indices]
      logit_list = self.head(feats)
      if not self.ms_attention:
          logit_list = [
              F.interpolate(
                  logit,
                  x.shape[2:],
                  mode="bilinear",
                  align_corners=self.align_corners,
              )
              for logit in logit_list
          ]
      return logit_list
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddleseg.cvlibs import manager, param_init
  from paddleseg.models import layers
label_desc: Use image node_id 2 for calling the OCRNetNV obj's underlying member method code with example usage: obj.forward(x) and returns: logit_list